Two wire thermostat on 4 wire electric baseboard heating

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Old 12-20-20, 07:17 AM
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Two wire thermostat on 4 wire electric baseboard heating

Hi, I am trying to replace my old mechanical thermostat for my electric baseboard heating so that I can have better control over the set temperature. I remove the old thermostat and disconnected the wires and there were 4 wires coming from the wall-two white and two black. The thermostat I bought is a Honeywell rlv3120 which only has two wires coming out the back. Can I wire this thermostat up to my current wires and if so how would I do it? If I can't, then do I need to buy a different thermostat or do I just have to stick with my old mechanical thermostat? Thank you for your help!
 
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Old 12-20-20, 07:22 AM
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Provided you meet the following condition, it can be used.
The RLV3120 thermostat CANNOT be used with a resistive load under 0.83, a resistive load over 8.3 a system driven by a contactor or a relay (inductive load), a fan-forced heating system (e.g. : fan-forced convector) or a central heating system.

You connect the white wires together and connect the thermostat to the two black wires.
 
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Old 12-20-20, 07:34 AM
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Hi, how many ft. of BB do you have?
Geo 🇺🇸
 
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Old 12-20-20, 09:28 AM
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If 240v you likely need a 4 wire/2 pole thermostat with "off" as it functions as a disconnect.
 
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Old 12-20-20, 10:08 AM
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I think it is a 240v because it is on a 20amp breaker. Do you have any recommendations for a good 4 wire/2 pole thermostat?
 
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Old 12-20-20, 10:11 AM
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I tried connecting the two wires together and the black wires to the thermostat but it sparked and I turned off the breaker.
 
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Old 12-20-20, 10:14 AM
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Yes....you would see a spark.
You should have the breaker off before making any wire changes.

That thermostat is limited to a maximum of 8.3amps @ 240v which is 2000 watts of heater.
 
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Old 12-20-20, 11:14 AM
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I had the breaker off when I was making the wire changes but after I turned it on was when I saw the spark. I guess I will probably need a higher rated them thermostat. Any recommendations on thermostats?
 
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Old 12-20-20, 11:40 AM
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You picked a digital thermostat.... is that what you want ?
Have you calculated how much wattage you have in heat strips ?
Just add the linear footage and let us know.

The Honeywell line pro stat is good for 3600 watts.
 
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Old 12-20-20, 03:54 PM
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It is probably about 20 linear feet
 
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Old 12-20-20, 04:04 PM
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That's close to 4500 watts. That would be a well loaded 20A 240v circuit.
 
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Old 12-20-20, 04:42 PM
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I have two separate baseboard heaters. Wasn't able to measure their exact length as I am not home but that is about what I estimate them to be. On a side note, are in wall heats like from cadet more efficient than electric baseboard?
 
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Old 12-20-20, 05:10 PM
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All electric heaters are 100% efficient. Every watt of heat is delivered into the house.
 
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Old 12-20-20, 06:36 PM
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I have old baseboard heaters. Would updating them to newer ones help me reduce my electric costs or would switching to wall heaters be better?
 
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Old 12-20-20, 07:40 PM
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Electric baseboards are slow acting heaters. Once they get warm they offer continuous heat.
A wall heater with a fan may heat the room quicker.

There is no loss with either type of heater so neither one is more efficient.... just maybe faster acting.
 
 

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